The Drug Induced Liver Injury Network (DILIN), funded by the National Institutes of Health in 2002, represents a critical strategy to mitigate the adverse consequences of DILI. Already, this extensive network of centers around the U.S. has cultivated an impressive repertoire of case-based clinical information and samples which will broaden our understanding of DILI. Initial work centered around retrospective data collection on DILI attributable to four drugs; amoxicillin/clavulanate, valproic acid, phenytoin, and isoniazid. Subsequent work, which is ongoing, involves the prospective accrual of incident cases of DILI from any drug or complementary and alternative medication. The purpose of this grant application is to contribute to the expansion of the DILIN through the participation of a large Philadelphia-based consortium; the Jefferson and University of Pennsylvania Health Systems represent the largest and second largest health care systems in the region, respectively. They draw adult and pediatric patients with hepatic disease from the region comprising Eastern Pennsylvania, Delaware, Southern and Central New Jersey, and Northern Maryland. Hepatology leaders from these health care systems have agreed to collaborate as a single clinical center for his grant. In addition, the Geisinger Health System will participate as a subsite of Jefferson; this component will extend the consortium's reach to include a large part of central Pennsylvania. The consortium will bring to DILIN a large ethnically and socioeconomically diverse population of patients. The specific aims of this proposal are as follows: 1) To identify bona fide adult and pediatric cases of DILI within the region comprising Eastern and Central Pennsylvania, Maryland, Delaware, and Southern and Central New Jersey; 2) To validate the accuracy of disease attribution, in conjunction with other members of DILIN; 3) To support a national network of centers devoted to the advancement of pharmacogenetic and pharmacoepidemiological study of DILI, by providing clinical information and samples; and 4) To participate in the development and maintenance of a website for use as an educational resource on DILI.